Actuators have come a long way since the invention of rotary motors, which set the foundation for robotics and marks the dawn of the age of automation and industrialization. The drastic improvement in performance of hard actuators nowadays is only matched by the large number of emerging soft actuators, which demonstrate functionalities tantamount to or more expansive than that of their hard counterparts. The most common mode of hard actuation—torsion, however, has very few realizations in soft actuator designs.
Robots or machines capable of complex movements often require many actuators working in synchrony. Such systems are potentially difficult to control. One way of reducing the complexity in control is to have parallel actuation in the system, where one or a few inputs can result in many outputs working synchronously in a desired way. For hard machines, parallel actuation can be realized through gears and levers in high precision. In soft machines, however, the counter parts of such parallel actuation systems are rare or non-existent.